The present invention relates, in general, to a tablet press, and more particularly to a tablet press of a type having a rotary turret for producing pellets.
FIG. 1 shows an exemplary configuration of a conventional tablet press. The conventional tablet press is hereby driven by a motor 2 which drives a cylindrical rotary turret 1 through a gear 4 and a toothed belt 5. The material is compressed in the rotary turret 1. The rotary turret 1 includes vertically extending bores, which are not shown in FIG. 1 for sake of clarity. The rotary turret 1 is filled via a filling unit 6 with a filling medium to be compressed to a tablet or pellet. Pressure is applied to the filling medium by way of two pressure rams via an upper idler pressure roller 7 and an additional lower idler pressure roller 8, thereby compressing the filling medium into a tablet or pellet.
FIG. 2 shows schematically the basic operating principle of the press. The rotary turret 1 is first filled by a filling unit 6. The pressing forces generated by the upper pressure roller 7 and the lower pressure roller 8 are then transferred to the filling medium 14 via an upper pressure ram 11 and a lower pressure ram 10, which for sake of clarity are only labeled once in FIG. 2, thereby compressing the filling medium 14 into the shape of a tablet. The pressed tablet is subsequently ejected.
The drive turns the rotary turret 1 so that the rotary turret 1 passes between the upper pressure roller 7 and the lower pressure roller 8 with a substantial force, thereby generating the pressing force onto the upper pressure ram 11 and the lower pressure ram 10.
Since the pressure rollers 7, 8 apply a significant force to the filling medium and the pressing force is generated at a high rate when the pressure rams pass under the pressure rollers, significant torque peaks and vibration excitations are applied to the entire mechanical system and/or to the drive train of the tablet press which includes the motor 2, the gear 4, the toothed belt 5 and the driveshaft 9. The generated mechanical vibrations place a significant load on the components of the drive train. The conventional elastic drive train can itself vibrate and thereby enhance the vibration spectrum which worsens the dynamic characteristics of the compression machine and the drive train. The large distance between rotary turret 1 and the actual motor 2 makes it difficult to produce a mechanically stiff system. Expensive mechanically damping means and complex control mechanisms may have to be employed to dampen the vibrations. Even with such complex damping arrangements, the vibration load can only be reduced so far, so that the mechanical components of the pellet press continue to be exposed to a high mechanical load.
It would therefore be desirable and advantageous to provide an improved tablet press which obviates prior art shortcomings and is able to specifically place significantly less stress on the mechanical components and the drive train of the tablet press due to vibrations.